I can't boot Ubuntu anymore [duplicate]

I have been using Ubuntu as my sole operating system on my Dell computer since 3 years. The battery pack of my computer is not working anymore, and in the past month my computer has been taken off the electric grid without closing down properly quite a number of times (I was staying with elderly family members who on multiple occasions just unplugged the device when they needed the plug). Recently I started getting notices of 'system program problem detected'. I reported these quite some times but my system was still working fine. Then I started having a problem with programs freezing while working in them, and the only solution was to once again just shut the computer down unproperly. A couple of days ago, I wanted to delete my Skype version in order to download a newer version, but while removing Skype, my computer froze again and I had to shutdown. Since then, I get the screen in the picture screenshot when trying to boot. I have only very limited knowledge about computers and commands etc. so I have no idea what to do. Does anyone know how I can fix this problem please?

[    0,044628] ACPI Error: [_SB_,PCI.RPO 5.PXSX] Namespace lookup failure, AE_NOT_FOUND (20170831/dswload2-191)
[    0.044637] ACPI Exception: AE_NOT_FOUND, lookup/catalog (20170831/psob.ject-253)
[    0.044639] ACPI Error: Ignore error and continue tablead (20170831/psobject-642)
[    0.044641] ACPI Error: Skip parsing opcode Scope (20170831/psloop-559)
[    0.044988] ACPI Error: [_SB_.PCI.RP 09.PXSX] Namespace lookup failure, AE_NOT_FOUND (20170831/dswload2-191)
[    0.044992] ACPI Exception: AE_NOT_FOUND, During name lookup/catalog (20170831/psobject-253)
[    0.044994] ACPI Error: Ignore error and continue table load (20170831/psobject-642)
[    0.044996] ACPI Error: Skip parsing opcode Scope (20170833/psloop-559)
[    1.298496] psmouse serio1: elantech: elantech_send_cmd query 0x02 failed.
[    1.298520] psmouse serio1: elantech: failed to query capabilities.
/dev/sda3 contains a file system with errors, check forced.
Inodes that were part of a corrupted orphan linked list found.

/dev/sda3: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY 
        (i.e., without -a or -p options)
fsck exited with status code 4
The root filesystem on /dev/sda3 requires a manual fsck


BusyBox v1.27.2 (Ubuntu 1:1.27.2-2ubuntu3.3) built-in shell (ash) Enter "help' for a list of built-in commands. (initramfs)

Solution 1:

Due to the sudden shutdowns the filesystem got corrupted. This might not be a problem as modern filesystems are quite resilient. Try running the fsck as suggested at the busybox prompt fsck -y /dev/sda3.